Hello, Greymalkin!

The problem does not involve the focus.

The cables of a suspension bridge are 50 ft above the roadbed at the ends of the bridge,

and 10 ft above it in the center of the bridge. .The bridge is 200 ft long.

Vertical cables are to be spaced every 20 ft along the bridge.

Calculate the lengths of these vertical cables.

Answers are: 10, 11.6, 16.4, 24.4, 35.6, 50Code:| * | * : | : :* | *: : * | * : : * | * : 50 : * * * : 50 : | : : |10 : : | : . - - * - - - - + - - - - * - - -100 | 100

I placed the parabola on a coordinate system.

The roadbed is the -axis.

The tops of the bridge are at

The lowest point is at

The equation has the form: .

Substitute

Substitute

Hence, the parabola is: .

Now, evaluate for